This invention pertains to sterilizing apparatus, and particularly to apparatus for sterilizing with steam and efficiently draining steam condensate from the apparatus. This invention is especially suitable for sterilizing fluid transfer conduits, such as those used in the pharmaceutical and biotech industries.
Typical prior art methods for draining condensate from steam sterilizing systems use steam traps. However steam traps have small, winding flow passages that are easily clogged. Once a steam trap is clogged, the apparatus to be sterilized will not be subjected to a sufficiently high temperature for a sufficiently long time to achieve sterilization. Government regulations, such as those of the Food and Drug Administration, typically require that items to be sterilized be subjected to a temperature of at least 120.5.degree. C. for about 60 minutes.
U.S. Pat. Nos. 4,261,382 and 4,505,427 (both to Bridges) relate to condensate drainage systems wherein a controlled valve is used instead of a steam trap. The temperature is measured by a sensor in the condensate drainage conduit. A temperature controller positions the valve, opening it when the temperature is too low and closing it when the temperature is too high. The trouble with the Bridges systems is that the portion of the conduit between the temperature sensor and the valve will always be filled with condensate that is below the sterilization temperature, thereby making it likely that portions of the equipment being sterilized will not be subjected to the full sterilizing temperature during the entire sterilization time.
The present invention overcomes this problem by locating the temperature sensor in the valve body, upstream of the valve closure, e.g. a diaphragm.
U.S. Pat. No. 4,336,821 (Frantz et al.) relates to a valve for draining liquid from a compressed gas reservoir having a sensor in the valve body. However, this sensor detects build up of liquid. The temperature in the valve body has nothing to do with whether the valve will open of close. Frantz et al. do disclose a temperature control device, but its purpose is to turn on a heater when the ambient temperature drops below a fixed point to prevent the valve from freezing. The flow of steam condensate is not regulated in response to system temperature.